Low-Profile Frequency-Reconfigurable Dielectric Patch Antenna and Array Based on New Varactor-Loading Scheme

A novel varactor-loading scheme is proposed for dielectric patch (DP) antenna to design frequency-reconfigurable antenna and array. Benefiting from the stacked structure of the DP antenna, the microstrip line is partially inserted between the DP and substrate in a simple way, and the extended part can be used to load the varactor, thereby realizing the function of frequency tunability. At the same time, the loading element has a slight effect on the radiation patterns of the proposed antenna. The impacts of the microstrip line dimensions on frequency tuning range (TR) and radiation efficiency of the antenna are investigated in detail. It is found that an appropriate inserted length of the microstrip line is a key to achieve a good tradeoff between the frequency TR and radiation efficiency. The resultant frequency-reconfigurable DP antenna shows a TR of about 15% and radiation efficiency of more than 50% across the frequency-TR. For demonstration, the DP antenna element and 2\times 2 array prototypes operating in the {C} -band are implemented and measured. The simulated and measured results with a good agreement are presented to verify the proposed idea.